The present invention concerns an airbag for vehicle-passenger protection devices that inflates rapidly in response to pyrotechnically generated gases and optionally to gases released from a compressed-gas cylinder. Airbags are now almost always made of polyamides or polyesters optionally coated at least to some extent with neoprene or silicon to protect the textile from the hot gases inflating the bag. Many manufacturers, instead of coating the critical areas of the textile, just add extra layers, which are intended to be sacrificed in defense of the main layer on the outside. Both measures--sacrificial layers of textile plus coats of neoprene or silicon--are sometimes also resorted to.
Gas generators or hybrids, that inflate airbags with a mixture of a pyrotechnically generated hot gas and a gas released from a cylinder that simultaneously cools, usually do not make it necessary to protect the airbag's textile from heat because the generators are designed to combine the hot and cool gases before they enter the bag thoroughly enough that the temperature of the mixture cannot threaten the textile. If a thorough enough mixture cannot be ensured, however, the bag's intake will be exposed to damage even from a hybrid generator.
Gas generators now employ azide-free propellants for various reasons. Such materials require higher ignition temperatures and accordingly release hotter gases.
Protecting airbag textiles from heat is accordingly becoming increasingly important if the advantages of azide-free propellants are still to be exploited.
Since the known and relevant methods of protection are all relatively expensive and complicated, there is a real need for simpler and cheaper but just as effective approaches.